Electrical ageing of polymers. The role of micro-domains

Polymer materials are disordered systems and their structure is continuously undergoing conformational changes called "the physical ageing". Furthermore, polymers exhibit a spatially varying morphology and a distribution of their properties and characteristics. In this article, the existence of micro-domains into polymer materials is proved, using an optical strain measurement technique. Then after, the role of these micro-domains is taken into consideration for a phenomenological description of their electrical ageing process. The different parameters affecting the ageing process, such as the local structure evolution and the local field value, are presented in a distributed way. In a first analysis the ageing process is described in a local scale. Afterwards, a statistical description of the totality of processes at play is necessary to present the global effect of the applied stress over the material structure which leads to the failure mechanism.